The pair won the Premier League title when working together with the Blues.
He told Il Mattino: "He's definitely one of the most attentive coaches I've ever had in my career. He's very demanding because he knows that to achieve your goals, you need to work, work, work.
"It might be hard for a player to get into his mindset at first, but when you see the results coming, you quickly understand that this is the right path to take."
Regarding his relationship with Conte, Hazard added: "Excellent, absolutely excellent. I still remember the fatigue after those training sessions, but over time I've appreciated their importance."
Hazard admits he's watching Napoli this season, with former teammates Kevin de Bruyne and Romelu Lukaku involved.
He also stated: "Napoli are going through a difficult period, mainly due to the numerous injuries. It's not every day that you have these injuries one after another. Conte knows how to do it. And that's why they can bounce back quickly and fight until the end to repeat the great feat of winning the Scudetto last year."
On De Bruyne, Hazard added: "I was happy to see him in a Napoli shirt. I hope that once he finally returns from the injury that struck him at the start of the season, he can help revive the team's fortunes. He certainly has the the quality, and his contribution will certainly be decisive in the final push."